Influenza, which is an epidemic viral respiratory infection, affects people of the wide age bracket from infants to the old aged and is often fatal. Currently controversial H5 avian influenza viruses that infect birds do not originally infect humans. However, human infection with the viruses was confirmed in Hong Kong in 1997 and was prevalent with the result that 6 of 18 patients died. Fortunately, no human infection had been confirmed thereafter. However, human infection was confirmed in Thailand and Vietnam in 2004 with the result that 8 and 16 persons died in Thailand and Vietnam, respectively.
Highly pathogenic avian influenza viruses include an H7 subtype, in addition to the H5 subtype. The H7 subtypes are broadly divided into Eurasian and American subtypes according to the sequences thereof. According to reports, the H7 avian influenza viruses killed 1 person when prevalent in Netherlands in 2003, and were also prevalent in USA from 2003 through 2004.
A kit for quick diagnosis of a human influenza virus A has been used currently in the detection of avian influenza viruses. However, the identification of a virus subtype that causes infection has required further detailed analysis such as the antigenic analysis or genetic test of separated viruses.
Diagnosis using virus separation and culture that produces accurate results requires several days and therefore, cannot be conducted quickly. There are several methods capable of quick diagnosis as compared with the virus separation. Among them, an RT-PCR method has been said to have high detection sensitivity as compared with other methods. However, according to some reports, currently disclosed RT-PCR methods cannot detect the viruses with high sensitivity as compared with viral infectivity. Thus, infection with an avian influenza virus cannot be denied even if a result is negative in a test using the RT-PCR method.
Thus, a test method capable of quickly detecting an H5 or H7 avian influenza virus with high sensitivity has been demanded.    Patent Document 1: European Patent Publication No. 1310565    Patent Document 2: Japanese Published PCT Translation No. 2004-509648    Non-Patent Document 1: Lau L T., et al., Biochem. Biophys. Res. Commun., vol. 313, p. 336-342 (2004)    Non-Patent Document 2: Shan S., et al., Biochem. Biophys. Res. Commun., vol. 302, p. 377-383 (2003)    Non-Patent Document 3: Collins R A., et al., Biochem. Biophys. Res. Commun., vol. 300, p. 507-515 (2003)    Non-Patent Document 4: Lee M S., et al., J. Virol. Methods, vol. 97, p. 13-22 (2001)    Non-Patent Document 5: Munch M., et al., Arch. Virol., vol. 146, p. 87-97 (2001)